1. Field of the Invention
This invention is in the field of polymer chemistry. Particularly, it concerns a process for hydrolyzing polymeric pendant amides to polymeric pendant amines.
2. The Prior Art
U.S. Pat. Nos. Re 30,362 of Gless et al and 4,176,136 of Brenzel disclose processes for preparing N-vinylacetamide. U.S. patent application Ser. No. 318,615 of Otteson et al filed Nov. 5, 1981 discloses a process for preparing N-vinylformamide. These references further disclose that these materials are polymerizable and that the resulting poly(N-vinylacetamide) or poly(N-vinylformamide) can be hydrolyzed to give poly(N-vinylamine). The possibility of N-alkyl substituted acetamides and amines is also taught by the art. Similar teachings in a copolymer setting are provided by the references listed in Table I.
TABLE I ______________________________________ Reference Comonomers ______________________________________ U.S. Pat. No. 4,255,548 ethylene U.S. Pat. No. 4,238,579 styrene U.S. Pat. No. 4,178,442 vinylsulfonate ______________________________________
The hydrolysis of these amide groups to amines is not facile. Typically, it has been carried out in refluxing aqueous acid, usually hydrochloric acid. This has two problems. First, few applications of the amine polymers (and certainly not their preferred applications in polymeric colorants) employ acid solutions. This means that the acid present must be removed or neutralized. Second, acidic conditions lead to a side reaction between neighboring amine and amide units--for example, ##STR1## These amidine units are an impurity that decreases the desired amine functionality of the hydrolyzed polymer and are to be avoided.